Douglas aircraft and ....

[Exhaustgases]

Douglas aircraft, I feel they did fine with aircraft design in the piston engine days, but started to go down hill when jets became the thing.

Too bad Boeing is part of this MD-11 stuff, I don't think Boeing had anything to do with the design??

And again touching on my comments in the now closed thread that was getting off topic.
My mention of out of country maintenance. Here strict measures to get an A&P license, I can't see it that strict else where, I worked with a fellow one time that was from another country that did work on aircraft, his aircraft mechanic knowledge was somewhat lacking, I think it was DC-3's he worked on, I know them fairly well.

 

[kschachn]

No, Boeing Seattle did not have design input on the MD-11. They had a very small input on the MD-95/717 but that was it.

 

[fdcg27]

Not really the case.
Douglas developed the DC-8 without government support and it did so in far less time than it took Boeing to bring the 707 to market. The DC-8 featured a much longer limit of validity than did the 707.
The same was true of the DC-9 versus the 727 or the 737. The DC-9 offered a limit of validity of 100K FH and 100K FC, far in excess of what either Boeing model offered. Some airlines used them that long as well, notably Northwest.
The DC-9 era continued for years with the MD-80 series, so beloved of American and Delta. The last DC-9 derivative is the 717, around a hundred of which continue carrying passengers today, mainly with Delta.
Nobody ever seriously questioned the design integrity or assembly quality of Douglas jets.
Then came the McDonnell merger.

 

[2005jettatdi]

Not really the case.
Douglas developed the DC-8 without government support and it did so in far less time than it took Boeing to bring the 707 to market. The DC-8 featured a much longer limit of validity than did the 707.
The same was true of the DC-9 versus the 727 or the 737. The DC-9 offered a limit of validity of 100K FH and 100K FC, far in excess of what either Boeing model offered. Some airlines used them that long as well, notably Northwest.
The DC-9 era continued for years with the MD-80 series, so beloved of American and Delta. The last DC-9 derivative is the 717, around a hundred of which continue carrying passengers today, mainly with Delta.
Nobody ever seriously questioned the design integrity or assembly quality of Douglas jets.
Then came the McDonnell merger.

The McDonnell seemingly destroyed Douglas and then when Boeing "bought out" McDonnell Douglas Boeing was destroyed when the MD people brought their build it cheap philosophy to Boeing.

The advantages 727s and 737s had over the DC 9 was the standard body width which allowed standard cargo containers to be loaded into the hold. I am not saying the DC 9 was not a good airplane, but I will say that about the MD 80.

 

[MNgopher]

Was going to say the same thing. The OP must be forgetting the long service history of the DC-9 series of aircraft and their long service lives that airlines like Northwest used with great success.

 

[fdcg27]

The McDonnell seemingly destroyed Douglas and then when Boeing "bought out" McDonnell Douglas Boeing was destroyed when the MD people brought their build it cheap philosophy to Boeing.

The advantages 727s and 737s had over the DC 9 was the standard body width which allowed standard cargo containers to be loaded into the hold. I am not saying the DC 9 was not a good airplane, but I will say that about the MD 80.

Not so sure about that. The single aisle Airbuses can accommodate containerized passenger baggage while the 737 is always bulk loaded AFAIK.
The McDonnell cheap-think philosophy ruined Douglas and has done much the same with Boeing.

 

[CleanSump]

I loved the F-4s I worked on, but they weren't airliners. I only know the go-fasters.
Boeing destroyed MD and NG.

 

[edyvw]

There is saying: “MD bought Boing with Boeing’s money.”

 

[kschachn]

Not really the case.
Douglas developed the DC-8 without government support and it did so in far less time than it took Boeing to bring the 707 to market. The DC-8 featured a much longer limit of validity than did the 707.
The same was true of the DC-9 versus the 727 or the 737. The DC-9 offered a limit of validity of 100K FH and 100K FC, far in excess of what either Boeing model offered. Some airlines used them that long as well, notably Northwest.
The DC-9 era continued for years with the MD-80 series, so beloved of American and Delta. The last DC-9 derivative is the 717, around a hundred of which continue carrying passengers today, mainly with Delta.
Nobody ever seriously questioned the design integrity or assembly quality of Douglas jets.
Then came the McDonnell merger.

104,000 cycles if I recall correctly. Even then, it wasn’t an ultimate design limit, there was a package of structural inspections and improvements that would have extended the limit beyond that. But because the airframe value was pretty depreciated by this time (mainly due to JT8D fuel consumption) it wasn’t economically viable. The most expensive component of the extension was replacement the aft pressure bulkhead.

But yes the structural integrity of the DC-9 was legendary.

 

[MolaKule]

Boeing decided that MD-11 support was unecceasry because it competed with their new, internal aircraft designs.

Google the history of the DC-10 and MD-11 on sites such as Wiki.

 

[MolaKule]

Douglas aircraft, I feel they did fine with aircraft design in the piston engine days, but started to go down hill when jets became the norm.

Douglas had competant aircraft design engineers and stress analysts. Many of my aircraft design and.analysis textbooks used Douglas aircraft designs as examples of good aircraft design.

The thing that changed the aircraft scene was that Boeing had more experience with jet powered aircraft.such as the 707 and B-52 designs.

 

[Exhaustgases]

Yes sort of forgot the DC-9's etc. I flew on a few of them and at the time had more trust for them over a 727, until the elevator trim screw disaster. And still can't understand the zero redundancy and not using ball screws.

 

[MNgopher]

Yes sort of forgot the DC-9's etc. I flew on a few of them and at the time had more trust for them over a 727, until the elevator trim screw disaster. And still can't understand the zero redundancy and not using ball screws.

Don't forget the multiple missed opportunities by Alaska Airlines maintenance at the time to detect the wear on the components that ultimately failed. A mechanic had even recommended the full replacement of the components years before the accident but was over ruled. While the single point of failure is an issue, it was only allowed to happen based on missing the opportunity to find it and prevent it by poor maintenance.

 

[Nyati]

A4s. They were good enough for the Blue Angels.

 

[kschachn]

Yes sort of forgot the DC-9's etc. I flew on a few of them and at the time had more trust for them over a 727, until the elevator trim screw disaster. And still can't understand the zero redundancy and not using ball screws.

What I can’t understand is how you think the trim screw was a design issue. That was strictly maintenance. Absolutely and completely. Had it been a design problem then the failures would have been systemic which they are not.

You post a lot, but you seem to understand very little.

 

[RedSpider]

The DC-9 jackscrew was 100% maintenance. If the original lube intervals issued by Douglas had been followed, there never would have been an issue. Problem was airlines flying them increased the interval 3x-6x times longer to reduce downtime, and thats when the problem started. I believe the AD that came out because of the Alaskan accident wasnt even as strict as Douglas' initial recommendation. I worked at Airborne during this time and of the 70-ish DC-9's in the fleet, I think only 2-3 jackscrew assemblies (I remember seeing them after they had been removed) ended up getting replaced, and even at that, it was out of an abundance of caution, Airborne had been following a tighter interval so it ended up being a bit of a nothingburger for us.

 

[edyvw]

Yes sort of forgot the DC-9's etc. I flew on a few of them and at the time had more trust for them over a 727, until the elevator trim screw disaster. And still can't understand the zero redundancy and not using ball screws.

It was maintenance issue.

 

[kschachn]

It was maintenance issue.

From the NTSB report:

The National Transportation Safety Board determines that the probable cause of
this accident was a loss of airplane pitch control resulting from the in-flight failure of the
horizontal stabilizer trim system jackscrew assembly's acme nut threads. The thread
failure was caused by excessive wear resulting from Alaska Airlines' insufficient
lubrication of the jackscrew assembly.

 

[TomYoung]

What I can’t understand is how you think the trim screw was a design issue. That was strictly maintenance. Absolutely and completely. Had it been a design problem then the failures would have been systemic which they are not.

You post a lot, but you seem to understand very little.

I would be a little circumspect here. The failure occurred suddenly and without warning. And there was no redundancy in this design to point to. Maintenance surely could have prevented this failure, but that doesn't give a complete pass on design.

 

[kschachn]

I would be a little circumspect here. The failure occurred suddenly and without warning. And there was no redundancy in this design to point to. Maintenance surely could have prevented this failure, but that doesn't give a complete pass on design.

True, Douglas was faulted for not having a fail-safe mechanism. However the cause of the failure was maintenance not following maintenance manual procedures, specifically not observing fresh grease extruding from the nut. The grease fittings were clogged with dried grease and as a result the nut and screw were never being properly lubricated.

In addition the mechanism play was not being measured properly which may have alerted maintenance to the excessive wear which was occurring due to insufficient lubrication. So in reality it was two failures in maintenance.

The lack of a fail-safe did not cause the failure. Had there been one it may have helped to prevent an accident, but on the other hand that family of aircraft had been operating for hundreds of thousands of hours and many decades prior to this accident. The accident itself may have been sudden but there was no technical reason it had to be that way.